Process for the conversion of chromate and bichromate of sodium or potassium to chromic sulfate



1-. M. MOONEY.

PROCESS FOR THE CONVERSiGN 0F CHROMATE AND BICHROIMAYE 0F SODIUM 0R POTASSIUM TO CHROMIC SULFATE- F a APPLiCATlON FILED MAY 22' I920. 1,8 (9 5 (80 Patemed May 2 C/z/omdam rabw/ds0dlzwz Sat/(26 Miguel" refrigeraid Glaubezis salt; and Cronu'wm viysials and [Lilac/1 Sana/wake! here 61.1 66 here Sat 012w dz'wwa/ 72 this Zara/i.

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Specification of Letters Patent.

OMATE 03F SODIUM 01ft Patented May 241, 19211..

Application filed may 22, 1920. Serial No. 383,599.

To all whom it may concern."

Beit known that I, FRANK MELBOURNE corner, 'a subject of the King of Great Britain, and residing at. 17 Sussex aveof Montreal,

in the Province of Quebec, in the Dominion of Canada, have invented Process for the Conversion of Chromate and ichromate of Sodium or Potassium to Chromic Sulfate, of which the following is .the specification.

he invention relates to a process for the conversion of bichromate or chromate of potassium or'sodium to chromic sulfate, as

more particularly described hereafter and pointed out in the claims for novelty.

he invention consists in the novel steps taken toward the union of known chemical substances, whereby with the aid of physical is brought about, as spedescription in deta1l.

The objects of the invention are to eliminate certain chemical substances used In many known processes of conversion, and to economize in the material utilized to obtain the chromic sulphate in the purest form.

y separating sodium salts, which tend to remove gelatin from hides, the chromic sulw fate solution is thus better adapted for use in tanning. Additional objects are to facilitate the manufacture concerned in the use of the substance by producing a richer and more effective generally to provide a liquor free from deleterious lnfluences in its ac tions on the fiberof the leather and comparatively cheap to make.

In the manufacture of the product the bichroinate of potassium sodium are first changed to chromium trioxid in the well known or approved manner by the use of sulfuric or other acids "'thenby a refrigeration step the temperature 0 F. till thesulfates formed become crystallized' t this stage the trioxid of'chromium solution is dralned of? through an extractor and by centrifugal operation the crystallized sodium salts are freed from the adhering chromium trioxid, and the latter is run into a separate tank where it is treated with sulfur dioxid generated by burning sulfur in a suitable plant.

a new and useful of sodium or article as the result of the and have a'tank of conslderable size, which con-- tains the trioxid that has been previousl prepared by means of the action of su r1c acid on the bichromate or chromate potassium. This tank indicated by the numeral 1 in: the accompanying diagrammatic drawing 1s associated with a refrigerating device 2, that so influences thle solution, as to crystallize the sodium sa ts.

The crystallized sodium salts and ii uor fiow to the extractor 3, which is contained within the casing 4 and rapidly rotated therein and as the extractor 3 is of screen form, the liquor leaves the sodium salts through. centrifugal force due to rotation and flows to the tank 5.

burning plant 6 is connected to 5 and th into and which chromium sulfate.

For those versed in the art, the following equation represents the final chemical action:

lit must be understood that some changes may be made without departing from the spirit of the invention.

What I claim is 1. The process of making chromic sulfate comprising the freeing by refri eration of a solution of .chrominum trioxid from Glaubers salt, the drawing off of the liquor containing chromium oxid and the charging of the said liquor with a reducing sulfur-containing gas.

2. The process of making chromic sulfate comprising the subjectin of a solution of chromium trioxid and laubers salt to a lowered temperature of approximately zero Fahn, and thereby crystallizing the salt, the withdrawal ofboth liquor andsalt for separation, the separation of the liquor and the tank e gas from said plant is directed thoroughly saturates the solution,

converts the chromium trioxid to the discharge of same to its receptacle and centrifugal action, the charging of the liquor the charging of the said liquor with a re-M with a reducing sulfur-containing gas and 10 ducin sulfur-containing gas. the Withdrawal of the salt to a separate re- 3. he process of making chromic sulfate ceptacle by dissolving the same. 5 comprising the refrigeration of a solution Signed at the city of Montreal, Quebec, of chromium trioxid and Glaubers salt to Canada, this 19th day of May 1920,

bring about the crystallization of the salt, the separation of the liquid from the salty by FRANK MELBOURNE MOONEY. 

